H5N1 bird flu spread: Warning for human transmissions as cases soar, mass mortality event established

The dangers of approaching sick or dead animals amid a bird flu outbreak have been reinforced after confirmation of the nation’s first mass mortality event.

The deadly H5 strain’s national tally continues to climb after a large group of dead and sick greater crested terns at Baudin Rocks in South Australia tested positive for the virus.

Another six were confirmed in Victoria, bumping the total number of positive cases in Australia to 78.

Associate Professor Lara Herrero, a specialist in infectious diseases and virology, said that while transmission of H5 to humans was rare, poultry industry workers and wildlife carers were the most vulnerable as the outbreak worsened.

She said H5 was spread in much the same way as human flu transmission - through close contact with airborne droplets and the bodily fluids of infected birds.

“It’s through contact with that, and then touching your face and getting it within your respiratory system, through your nose and your mouth,” she told AAP.

“The most common way a human is going to get this is from infected poultry, so the highest risk in that regard is poultry workers.”

While no cases of bird flu have yet been detected in the Australian poultry industry, losses worldwide have been estimated at 140 million birds.

Prof Herrero said while H5 transmission to livestock was also very rare, there had been cases in the United States where dairy farmers had become infected because the virus could enter the milk of infected cows.

Wildlife carers and veterinarians were also at higher risk and needed to wear personal protective equipment, she said.

“It’ll look similar to during COVID, to be honest,” she said.

“You want your N95 masks, you want gloves, you want to avoid any contact with infected airborne droplets, any fluid or anything that can be transmitted into your respiratory system.”

Human deaths were extremely rare, with the virus producing symptoms similar to flu, she said.

However, she said those symptoms could be more severe.

“It’s usually more extreme in that the symptoms are worse - higher fevers, sore throat, bigger headaches,” she said.

There was also a higher correlation of conjunctive and gastrointestinal symptoms.

Prof Herrero also sounded a warning for people to strictly control their dogs on beaches to prevent them from investigating or attacking sick birds.

“If you have a dog that has been in close contact with a sick bird, I would quarantine your dog,” she said.

People are advised not to approach or touch any sick birds they find, and to report suspected cases to the Emergency Animal Disease Hotline on 1800 675 888, recording the date, time and location.